Water-soluble film for packaging chemicals

Abstract

Provided is a water-soluble film which is for packaging chemicals and contains a polyvinyl alcohol resin, and with which a molded capsule can maintain the height thereof with as much tension as possible even after storage while preventing adhesion between films and bleed-out of a plasticizer.　This water-soluble film contains a water-soluble resin obtained by blending a plasticizer (B) with a polyvinyl alcohol resin (A), wherein: the polyvinyl alcohol resin (A) has a degree of saponification of 85-96 mol%, a 4% aqueous solution viscosity of 6-50 mPa∙s, and a maleic acid-modified monomer unit amount of 0.2-1.6 mol%; the blending amount of the plasticizer (B) is 5-50 parts by mass with respect to 100 parts by mass of the polyvinyl alcohol resin (A); and the moisture content of said film is 4.0-10.0 mass%.

Description

Water-soluble film for pharmaceutical packaging

[0001] The present invention relates to a water-soluble film for packaging medicines.

[0002] In recent years, an increasing number of chemicals, such as detergents and pesticides, are packaged in capsules made of water-soluble film, containing a predetermined amount of chemical. By adding a predetermined amount of water to the capsule, the water-soluble film dissolves, dispersing or dissolving the chemical in the water, achieving a desired concentration and simplifying handling. Many of these capsules are made of a water-soluble film containing a polyvinyl alcohol resin as the primary component and a plasticizer. Because unmodified polyvinyl alcohol resins have high crystallinity, water-soluble films made of unmodified polyvinyl alcohol resins often have a poor dissolution rate, especially in cold water. For this reason, anionic group-modified polyvinyl alcohol resins modified with an anionic component such as a carboxylic acid are used to improve the water solubility of water-soluble films containing polyvinyl alcohol resins.

[0003] However, although water-soluble films containing anionic group-modified polyvinyl alcohol resins have improved water solubility compared to water-soluble films made of unmodified polyvinyl alcohol resins, when the resulting pharmaceutical packaging capsules are filled with liquid detergent and stored, the capsules lose their tension, their height decreases, and their appearance deteriorates. To prevent this loss of tension in pharmaceutical packaging capsules, Patent Document 1 below proposes a water-soluble film for packaging liquid detergents, in which an anionic group-modified polyvinyl alcohol-based resin is blended with a polyhydric alcohol such as glycerin or sorbitol as a plasticizer. Thus, pharmaceutical packaging capsules made of a film containing a polyhydric alcohol as a plasticizer can reduce the migration of the polyhydric alcohol between the film and the liquid detergent, thereby maintaining the capsule tension, even when a liquid detergent containing a polyhydric alcohol is encapsulated.

[0004] However, due to the need to balance the polyhydric alcohol contained in the liquid detergent and the film, when attempting to encapsulate a liquid detergent with a high concentration of polyhydric alcohol, it is necessary to increase the amount of polyhydric alcohol used as a plasticizer in the film, which could result in adhesion between the films or bleeding out of the plasticizer.

[0005] Patent No. 6809227

[0006] The present invention aims to solve the above-mentioned problems and to provide a water-soluble film containing a polyvinyl alcohol resin, which prevents adhesion of films to each other and bleed-out of plasticizer, and allows the formed capsules to maintain their tension and height as much as possible even after storage.

[0007] The water-soluble film for pharmaceutical packaging that achieves the above-mentioned object is a water-soluble film containing a water-soluble resin in which a plasticizer (B) is blended with a polyvinyl alcohol resin (A), wherein the polyvinyl alcohol resin (A) has a degree of saponification of 85 to 96 mol%, a 4% aqueous solution viscosity of 6 to 50 mPa·s, and contains 0.2 to 1.6 mol% of maleic acid-modified monomer units, and the blending amount of the plasticizer (B) is 5 to 50 parts by mass per 100 parts by mass of the polyvinyl alcohol resin (A), and the moisture content of the film is 4.0 to 10.0% by mass.

[0008] The polyvinyl alcohol resin (A) is preferably a maleic acid-modified polyvinyl alcohol resin, since this improves the water solubility of the water-soluble film.

[0009] It is preferable that the amount of the maleic acid-modified monomer unit contained in the polyvinyl alcohol resin (A) is 0.2 mol % or more and less than 1.0 mol %, since this allows the height of capsules produced using the water-soluble film to be better maintained.

[0010] It is preferable that the plasticizer (B) is glycerin (B-1) or glycerin (B-1) and diglycerin (B-2), since this can impart flexibility to the water-soluble film and prevent adhesion between water-soluble films and bleeding out of the plasticizer.

[0011] The water-soluble film for drug packaging according to the present invention contains a water-soluble resin made of a polyvinyl alcohol resin containing a predetermined amount of maleic acid-modified monomer, which has a predetermined range of saponification degree and viscosity, and is blended with a predetermined range of plasticizer in a blend amount, and can be formed while preventing adhesion between films and bleeding out of the plasticizer, and can also easily mold drug packaging capsules. The molded drug packaging capsules maintain their tension and height as much as possible over time, and have a good appearance.

[0012] 1 is an explanatory diagram illustrating the initial height h1 of a capsule using a water-soluble film for packaging medicines and the height h2 after storage. FIG.

[0013] The resin forming the water-soluble resin contained in the water-soluble film for pharmaceutical packaging of the present invention (hereinafter simply referred to as the water-soluble film) is a polyvinyl alcohol resin (hereinafter referred to as a PVA resin) containing 0.2 to 1.6 mol% of maleic acid-modified monomer units. Examples of maleic acid-modified monomer units include, but are not limited to, maleic acid, monoalkyl maleates, monomethyl maleates, and alkali metal salts thereof. Monomethyl maleate is particularly preferred from the viewpoint of the solubility of pharmaceutical packaging capsules. The amount of maleic acid-modified monomer units contained in this PVA resin is 0.2 to 1.6 mol%, preferably 0.2 to 1.4 mol%, more preferably 0.2 to 1.2 mol%, even more preferably 0.2 mol% or more but less than 1.0 mol%, even more preferably 0.5 mol% or more but less than 1.0 mol%, and particularly preferably 0.5 to 0.9 mol%, which is preferred because it facilitates achieving both the solubility of the film and the tension of capsules packaged with the water-soluble film. Water-soluble films made of PVA resins containing less than 0.2 mol% maleic acid-modified monomer units tend to have reduced water solubility, while capsules formed from the resulting water-soluble film containing more than 1.6 mol% maleic acid-modified monomer units may lose their tension over time, resulting in a reduced height and poor appearance. PVA resins containing 0.2 to 1.6 mol% maleic acid-modified monomer units may be polymerized by adding a predetermined amount of maleic acid monomer during polymerization, or by mixing unmodified PVA resin and maleic acid-modified PVA resin to obtain a PVA resin with a predetermined amount of maleic acid-modified monomer units. Furthermore, two or more maleic acid-modified PVA resins containing the same or different amounts of maleic acid-modified monomer units may be mixed to obtain a PVA resin with a predetermined amount of maleic acid-modified monomer units. When two or more PVA resins are mixed to obtain a PVA resin having a predetermined amount of maleic acid-modified monomer units, the amount of maleic acid-modified monomer units in the PVA resin can be calculated as a weighted average amount obtained by adding the product of the amount of maleic acid-modified monomer units of each PVA resin to be mixed and the mass percentage of each PVA resin. The calculation formula is shown below.

[0014] M = Σ(W i ・mi ) M: Weighted average amount (mol%) of maleic acid-modified monomer in PVA resin W i : mass% of maleic acid-modified monomer of the i-th PVA resin m i : Amount (mol %) of maleic acid-modified monomer units of the i-th PVA resin In particular, it is preferable that the PVA resin consists of a maleic acid-modified PVA resin, since the solubility of the water-soluble film can be easily adjusted.

[0015] The saponification degree of the PVA resin used in the present invention is 85 to 96 mol%, preferably 88 to 92 mol%, and more preferably 88 to 90 mol%. A PVA resin with a saponification degree within this range allows for easy adjustment of its water solubility. Furthermore, as long as the saponification degree is within this range, only one PVA resin may be used, or two or more PVA resins with the same or different saponification degrees may be used in combination. When two or more PVA resins are mixed to obtain a PVA resin with a predetermined saponification degree, the saponification degree of the PVA resin can be calculated as a weighted average amount obtained by adding the product of the saponification degree and the mass percentage of each PVA resin to be mixed. The calculation formula is shown below.

[0016] H ０ =Σ(W j ・H j ) H ０ W: Weighted average of the saponification degree of the PVA resin (mol%) j : mass% of jth PVA resin H j : Saponification degree (mol %) of j-th PVA resin. The saponification degree can be measured in accordance with JIS K6726 (1994).

[0017] Furthermore, the viscosity of the PVA resin in a 4% by weight aqueous solution at 20°C is 6 to 50 mPa·s, preferably 8 to 30 mPa·s, and more preferably 10 to 28 mPa·s. Using a PVA resin with a 4% by weight aqueous solution viscosity within this range results in excellent solubility of the water-soluble film and high strength. If the 4% by weight aqueous solution viscosity is less than 6 mPa·s, the mechanical properties of the water-soluble film and the pressure resistance of the final detergent packaging capsule tend to be reduced, while if the 4% by weight aqueous solution viscosity exceeds 50 mPa·s, the water solubility of the water-soluble film tends to be reduced. Furthermore, as long as the 4% by weight aqueous solution viscosity is within this range, only one PVA resin may be used, or two or more PVA resins with the same or different 4% by weight aqueous solution viscosities may be used in combination. When two or more PVA resins are mixed to obtain a PVA resin with a predetermined 4% by weight aqueous solution viscosity, the 4% by weight aqueous solution viscosity of the PVA resin can be calculated as a weighted natural logarithm average. The calculation formula is shown below.

[0018] lnμ = Σ(W n ・lnμ n μ: Weighted natural logarithm average of the viscosity of a 4% by mass aqueous solution of the PVA resin (mPa s) W n : mass% μ of n-th PVA resin n : Viscosity (mPa·s) of a 4% by mass aqueous solution of the nth PVA resin. The viscosity of a 4% by mass aqueous solution can be measured in accordance with JIS K6726 (1994).

[0019] The PVA resin can be obtained by polymerizing a polymer by a known method, such as solution polymerization, bulk polymerization, or suspension polymerization, and then saponifying the polymer. The saponification is carried out using an alkali or an acid, and the use of an alkali is particularly preferred.

[0020] The PVA resin used in the present invention may contain repeating units composed of the following monomers, provided that the effects of the present invention are not impaired. Examples of such monomers include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene, complete alkyl esters of unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, and itaconic acid, nitriles such as acrylonitrile and methacrylonitrile, amides such as acrylamide and methacrylamide, alkyl vinyl ethers, 2-acrylamido-2-methylpropanesulfonic acid, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethyldiallylammonium chloride, dimethylallyl vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, and polyoxyethylene (meth)allyl ether. Examples of the polyoxyalkylene (meth)allyl ether include polyoxypropylene (meth)allyl ether, polyoxyalkylene (meth)acrylates such as polyoxyethylene (meth)acrylate and polyoxypropylene (meth)acrylate, polyoxyalkylene (meth)acrylamides such as polyoxyethylene (meth)acrylamide and polyoxypropylene (meth)acrylamide, polyoxyethylene (1-(meth)acrylamide-1,1-dimethylpropyl) ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine, and diacrylacetonamide.

[0021] Further examples include cationic group-containing monomers such as N-acrylamidoethyltrimethylammonium chloride, N-acrylamidopropyltrimethylammonium chloride, 2-acryloxyethyltrimethylammonium chloride, 2-methacryloxyethyltrimethylammonium chloride, 2-hydroxy-3-methacryloyloxypropyltrimethylammonium chloride, methallyltrimethylammonium chloride, 3-butenetrimethylammonium chloride, and diethyldiallylammonium chloride.

[0022] The degree of polymerization of the PVA resin is preferably 700 to 2500, more preferably 900 to 2000, and even more preferably 1000 to 1700. If the degree of polymerization is less than 700, the mechanical properties of the water-soluble film and the pressure resistance of the final detergent packaging capsule tend to decrease, while if the degree of polymerization exceeds 2500, the water solubility of the water-soluble film tends to decrease. Furthermore, as long as the degree of polymerization is within this range, only one type of PVA resin may be used, or two or more PVA resins having the same or different degrees of polymerization may be used in combination.

[0023] The water-soluble film of the present invention contains 5 to 50 parts by mass of plasticizer (B) per 100 parts by mass of PVA resin, preferably 8 to 40 parts by mass, and more preferably 10 to 35 parts by mass. Blending the plasticizer (B) within this range provides flexibility to the water-soluble film and prevents the plasticizer from bleeding out, which is preferable. If the plasticizer (B) is less than 5 parts by mass, the water-soluble film lacks flexibility and processability decreases, while if the plasticizer (B) is more than 50 parts by mass, the plasticizer bleeds out, making the film prone to stickiness. The plasticizer (B) preferably contains glycerin (B-1) or glycerin (B-1) and diglycerin (B-2). When the plasticizer (B) contains glycerin (B-1) alone, the glycerin (B-1) is blended in an amount of 5 to 50 parts by mass, preferably 8 to 40 parts by mass, and more preferably 10 to 35 parts by mass, per 100 parts by mass of PVA resin. Furthermore, when the plasticizer (B) contains glycerin (B-1) and diglycerin (B-2), it is preferable to blend 5 to 45 parts by mass, preferably 5 to 35 parts by mass, and more preferably 16 to 33 parts by mass of glycerin (B-1) and 5 to 45 parts by mass, preferably 5 to 35 parts by mass, and more preferably 16 to 33 parts by mass of diglycerin (B-2) relative to 100 parts by mass of the PVA resin. By blending glycerin (B-1) or glycerin (B-1) and diglycerin (B-2) as the plasticizer (B) within such ranges, it is possible to achieve the effect of improving the flexibility of the water-soluble film while preventing bleed-out of the plasticizer.

[0024] The water-soluble film for packaging pharmaceuticals of the present invention has a moisture content of 4.0 to 10.0% by mass under normal temperature, pressure, and humidity conditions. This moisture content is more preferably 4.5 to 9.0% by mass, and even more preferably 5.5 to 8.0% by mass. If the moisture content is less than 4.0% by mass, the flexibility of the water-soluble film tends to decrease, and if the moisture content exceeds 10.0% by mass, the water-soluble film tends to adhere to itself.

[0025] The plasticizer (B) used in the present invention is preferably composed of glycerin (B-1) or glycerin (B-1) and diglycerin (B-2), as this allows production without requiring complex production equipment. However, the plasticizer (B) may contain other plasticizers besides glycerin (B-1) and diglycerin (B-2), as long as the blending amount of the plasticizer (B) is within the above-mentioned range and the above-mentioned effects are achieved. Examples of other plasticizers include polyethers such as diethylene glycol, trimethylolpropane, triethylene glycol, dipropylene glycol, propylene glycol, 2-methyl-1,3-propanediol, and polypropylene glycol; phenol derivatives such as bisphenol A and bisphenol S; sugar alcohols such as sorbitol, mannitol, xylitol, and pentaerythritol; amide compounds such as N-methylpyrrolidone; compounds obtained by adding ethylene oxide to polyhydric alcohols such as pentaerythritol and sorbitol; and polyethylene glycols such as PEG 200 and PEG 400.

[0026] When glycerin (B-1) and diglycerin (B-2) are blended as the plasticizer (B), the blending ratio of glycerin (B-1) to diglycerin (B-2), (B-2 / B-1), is preferably 10 / 90 to 80 / 20, more preferably 20 / 80 to 50 / 50, and even more preferably 20 / 80 to 40 / 60, since the water-soluble film can be wound up without adhering to a roll or the like during production. By adjusting the blending ratio of glycerin (B-1) to diglycerin (B-2) within the above range, the effect of improving the processability of the water-soluble film can be achieved.

[0027] The PVA resin used in the present invention has a predetermined saponification degree, viscosity, and contains 0.2 to 1.6 mol% maleic acid-modified monomer units. Therefore, the PVA resin may yellow due to heating during film formation or molding of the resulting water-soluble film. Even capsules containing detergents or other pharmaceuticals formed from the resulting water-soluble film may become discolored over time due to deterioration during storage. To prevent such yellowing and deterioration, it is preferable to contain a sulfite as an antioxidant. Examples of sulfite include sodium sulfite, sodium bisulfite, sodium pyrosulfite, potassium sulfite, potassium pyrosulfite, calcium sulfite, and ammonium sulfite. Sodium sulfite is particularly preferred. These sulfites may be used alone or in combination. Furthermore, the sulfite contained in the water-soluble film for pharmaceutical packaging capsules may be the same as or different from the sulfite contained in the detergent or other pharmaceuticals to be encapsulated. However, water-soluble films containing a large amount of sulfite may precipitate sulfite during storage. For this reason, the content of the sulfite is preferably 0.1 to 1.9 parts by mass, more preferably 0.5 to 1.5 parts by mass, and even more preferably 0.8 to 1.1 parts by mass, per 100 parts by mass of the PVA resin. A sulfite content within this range can prevent yellowing due to heating during film formation or molding, and coloring of capsules containing a detergent, and can also prevent precipitation of the sulfite during storage of the formed water-soluble film.

[0028] The water-soluble film containing the PVA resin used in the present invention can contain other additives within a range that does not impair the physical properties of the resulting water-soluble film. Examples of other additives include surfactants, water-soluble polymers, and additives. Examples of surfactants include nonionic surfactants, anionic surfactants, cationic surfactants, and zwitterionic surfactants. Among these, preferred surfactants are polyoxyethylene alkyl ether phosphate ester salts, polyoxyethylene lauryl ether acetate sodium salts, polyoxyethylene alkyl ether phosphate potassium salts, di-2-ethylhexyl sulfosuccinate sodium salts, and polyoxyethylene alkyl ether sulfate sodium salts. These surfactants may be used alone or in combination. The content of the surfactant is preferably 0.03 to 1.00 parts by mass, more preferably 0.1 to 0.7 parts by mass, and even more preferably 0.2 to 0.4 parts by mass, per 100 parts by mass of the PVA resin. The surfactant can impart releasability from the cast surface during production of the water-soluble film, and can also facilitate processing such as sealing (water sealing, heat sealing) when producing pharmaceuticals, particularly liquid detergent packaging capsules, powder detergent packaging capsules, or packaging capsules containing powder detergent and liquid detergent.

[0029] Examples of water-soluble polymers include sodium polyacrylate, polyethylene oxide, polyvinylpyrrolidone, dextrin, chitosan, chitin, methylcellulose, hydroxyethyl cellulose, etc. Examples of additives include various fillers such as silica, aluminosilicate (zeolite), titanium oxide, talc, starch, and crosslinked acrylic fine particles, colorants, fragrances, extenders, antifoaming agents, release agents, ultraviolet absorbers, rust inhibitors, liquid paraffins, fluorescent brighteners, chelating agents, bittering agents such as denatonium benzoate, fatty acid substances, and inorganic powders.

[0030] The method for producing a water-soluble film for packaging medicines of the present invention includes a step of preparing an aqueous solution and a film-forming step of producing a water-soluble film.

[0031] The method for preparing the aqueous solution is not particularly limited, but examples include dissolving PVA resin and additives such as plasticizers, surfactants, and fillers in a dissolution tank or kneading the PVA resin in a water-containing state with additives such as plasticizers, surfactants, and fillers using a twin-screw extruder. The method for producing a water-soluble film containing a PVA resin is not particularly limited, but examples include a method in which an aqueous solution or aqueous solvent solution of a water-soluble film composition containing a PVA resin is supplied to the surface of a rotating metal roll or other support member (including a metal belt surface) using a known device, and then peeled from the surface of the metal roll or other support member (including a metal belt surface) and wound up while drying. This supplying method can be performed using known means such as a solution casting method (casting method) or a roll coating method. Furthermore, if necessary, the water-soluble film can be embossed, for example, by applying an embossed pattern to the water-soluble film by heating and pressing it between two rollers having embossed irregularities on the surface.

[0032] The thickness of the water-soluble film for medicinal packaging of the present invention obtained by film formation is preferably 40 to 120 μm, more preferably 50 to 110 μm, and even more preferably 60 to 90 μm. Water-soluble films with a thickness of less than 40 μm tend to have insufficient tensile strength for use in medicinal packaging capsules, while water-soluble films with a thickness of more than 120 μm tend to have reduced moldability when formed into medicinal packaging capsules.

[0033] The obtained water-soluble film for medicinal packaging may be formed from only one layer, or may be formed by laminating two or more layers of the same or different water-soluble films having the same composition as the water-soluble film. A detergent packaging capsule using such a water-soluble film is formed by bonding the edges of at least two sheets of water-soluble film together, and contains a medicinal agent such as a detergent. Furthermore, the medicinal packaging capsule is produced by filling and sealing the contents with heat sealing or water sealing. The medicinal packaging capsule is preferably formed by a thermoforming method or a vertical-form-fill-seal (VFFS) method, and more preferably formed by a thermoforming method.

[0034] Here, a drug-packaged capsule produced by a thermoforming method can be produced, for example, by forming a water-soluble film along the inner wall surface of a cavity of a predetermined capacity formed in a mold to form a bottom water-soluble film with a recess of a predetermined capacity, filling the recess with a predetermined amount of drug, applying a predetermined amount of water to one side of a top water-soluble film made of a water-soluble film, and crimping a predetermined surface of the bottom water-soluble film located on the periphery of the cavity of the mold with the water-coated surface of the top water-soluble film. Furthermore, the depth of the drug-packaged capsule can be appropriately adjusted within a range that can withstand deep drawing. Furthermore, a drug-packaged capsule produced by a VFFS method can be produced by folding a water-soluble film vertically, sealing the overlapping edges by heating vertically and horizontally, filling the folded water-soluble film with a drug, and sealing the top.

[0035] The medicinal packaging capsule formed from the water-soluble film for medicinal packaging of the present invention may contain a powder detergent and a liquid detergent and / or a gel detergent as medicinal products. It may also be used as a single-package, multi-chamber detergent packaging capsule in which a powder detergent or a liquid detergent is packaged alone, or two or more detergents, a powder detergent and a liquid detergent, are packaged separately. It may also be an agrochemical packaging capsule in which an agrochemical is packaged as medicinal products.

[0036] Incidentally, when a water-soluble film formed only from unmodified PVA resin comes into contact with alkaline substances and / or substances with a high moisture content, such as powder detergents or liquid detergents, the PVA resin undergoes a hydrolysis reaction to undergo saponification, and the solubility of the film is likely to decrease. Therefore, even if the water-soluble film of a detergent-filled capsule has good solubility immediately after the capsule is manufactured, if time passes before the capsule is used, the saponification of the water-soluble film will progress and the water-soluble film of the capsule will likely remain undissolved.

[0037] In this regard, with regard to the water-soluble film for pharmaceutical packaging according to the present invention, as described below, when a solubility evaluation test was conducted in which a detergent-contacted water-soluble film having a thickness of 75 μm was contacted with a liquid detergent having a pH of 7 to 8 measured in accordance with JIS K 3362 8.3 for 14 days in an environment of 40°C and 80% RH, and a detergent-uncontacted water-soluble film having a thickness of 75 μm before contact with the detergent were each immersed in water at 20°C, the difference between the time for complete dissolution of the detergent-contacted water-soluble film and the time for complete dissolution of the detergent-uncontacted water-soluble film was 182 seconds or less, and the complete dissolution time of the detergent-contacted water-soluble film was 246 seconds or less. Furthermore, when a similar solubility evaluation test was conducted using a powder detergent having a pH of 10 to 11 measured in the same manner instead of the liquid detergent, the difference between the time for complete dissolution of the detergent-contacted water-soluble film and the time for complete dissolution of the detergent-uncontacted water-soluble film was 35 seconds or less, and the complete dissolution time of the detergent-contacted water-soluble film was 78 seconds or less. In this way, the water-soluble film for packaging medicinal products according to the present invention has a short dissolution time for the water-soluble film forming the detergent packaging capsule containing the liquid detergent, and can prevent the dissolution time from being longer than the dissolution time for the water-soluble film of the detergent packaging capsule before the liquid detergent is enclosed.

[0038] The water-soluble film for packaging medicinal products according to the present invention was formed into a 75 μm-thick water-soluble film to obtain spindle-shaped capsules as shown in FIG. 1(a). The initial height h1 shown in FIG. 1(a) was 24.3 to 26.9 mm, but after storage for 7 days in an environment of 23°C and 50% RH, the capsule height h2 became lower than the initial height h1, as shown in FIG. 1(b). For capsules using the water-soluble film for packaging medicinal products according to the present invention, the difference (h1 - h2) between the initial height and the capsule height after 7 days of storage was 4.7 mm or less. Because the capsule's tension could be maintained as much as possible, the capsule's original appearance could be substantially maintained over time.

[0039] Examples of the present invention will be described in detail below, but the scope of the present invention is not limited to these examples.

[0040] (PVA Resin) Six types of maleic acid-modified PVA resins and an unmodified PVA resin were used as PVA resin (A). The average degree of polymerization, degree of saponification, and viscosity of a 4% by mass aqueous solution at 20°C (hereinafter referred to as "4% by mass aqueous solution viscosity") of each resin are shown in Table 1 below.

[0041]

[0042] The following additives were added to the maleic acid-modified PVA resin and unmodified PVA resin shown in Table 1 in the amounts shown in Table 2. (Additives) Plasticizer (B): Glycerin (B-1) Diglycerin (B-2) Antioxidant (C): Sodium sulfite Surfactant (D): Polyoxyethylene alkyl ether phosphate potassium salt

[0043]

[0044] The modification degrees, saponification degrees, and 4% by mass aqueous solution viscosities of PVA resins No. 1 to 16 shown in Table 2 are shown in Table 3. Note that the modification degrees, saponification degrees, and 4% by mass aqueous solution viscosities of PVA resins mixed with two or more types of PVA resins are the results of calculations based on the above-mentioned calculation method.

[0045]

[0046] (Preparation of Water-Soluble Film Compositions Nos. 1 to 6) A total of 100 parts by mass of the PVA resin shown in Table 1, the plasticizer, antioxidant, surfactant, and water shown in Table 2 were added and kneaded to prepare water-soluble film compositions. (Film Formation of Nos. 1 to 6) The viscosity of this composition was approximately 3000 mPa·s when measured at 85°C using a Brookfield viscometer. A metal roll was prepared as a casting surface, and its surface was cleaned by wiping with a cloth moistened with pure water. While heating the surface of the metal roll to approximately 80 to 95°C, the water-soluble film composition was cast onto the metal roll. The metal roll was dried for 8 minutes while rotating, producing a 75 μm-thick water-soluble film for liquid detergent packaging capsules. The moisture content of the resulting water-soluble film was measured in accordance with JIS K 6726 3.4, and the resulting volatile content value was measured as the moisture content.

[0047] (Preparation of Water-Soluble Film Compositions Nos. 7 to 16) A total of 100 parts by mass of the PVA resin shown in Table 1 was used, and the above-mentioned plasticizer, antioxidant, and surfactant were added as shown in Table 2. The mixture was kneaded in a wet state using a twin-screw extruder to prepare a water-soluble film composition with a concentration of 55 to 59% by mass. (Formation of Water-Soluble Film Compositions Nos. 7 to 16) The water-soluble film compositions prepared to the compositions shown in Tables 2 and 3 were cast from a T-die at 90°C onto the surface of a metal roll (first drying roll) whose surface temperature was maintained at 86°C. While the metal roll (first drying roll) was rotating, the film was dried for 80 seconds, peeled from the first drying roll, and further dried with the second drying roll and subsequent drying rolls so that one side of the PVA film alternately contacted each drying roll, thereby forming a water-soluble film with a thickness of 75 μm. The moisture content of the resulting water-soluble film was measured in accordance with JIS K 6726 3.4, and the resulting volatile content was taken as the moisture content.

[0048] The initial solubility of each of the water-soluble films obtained from the water-soluble film compositions shown in Table 2 was evaluated by the solubility evaluation test shown below, and the results are shown in Table 4. (Evaluation Test for Initial Solubility of Water-Soluble Films) A film sample piece cut to 39 mm x 32 mm was sandwiched between two rectangular plastic mounts with 34 mm x 23 mm windows, respectively, so that the windows were blocked, and the film was fixed to a hanging jig. Next, a water bath containing 800 mL of distilled water in a 1 L beaker and maintained at 20°C was stirred with a stirrer (stirring bar length: approximately 5 cm, rotation speed: 400 rpm). A 75 μm-thick water-soluble film sample piece fixed to a plastic mount attached to a hanging jig was immersed in water in the water bath, and the time when the water-soluble film sample piece broke anywhere in the water-soluble film sample was measured as the initial dispersion time (dispersion time of the detergent-uncontacted water-soluble film). After checking this initial dispersion time, the plastic mount was struck up and down to knock the water-soluble film sample pieces off the plastic mount, so that the water-soluble film sample pieces floated in the water. The time when the water-soluble film sample pieces were completely dissolved and no remaining pieces could be visually confirmed was measured as the initial complete dissolution time (the complete dissolution time of the detergent-uncontacted water-soluble film). Note that "dissolution" also includes the case where insoluble fine particles with a diameter of 1 mm or less were dispersed at the time when the water-soluble film sample pieces could no longer be visually confirmed.

[0049] The solubility of water-soluble films obtained from the water-soluble film compositions shown in Table 2 after detergent contact treatment was evaluated by the following solubility evaluation test, and the results are also shown in Table 3. (Test for evaluating solubility of water-soluble films after detergent contact treatment) A 50 mL glass bottle was charged with 65 g of liquid detergent A (consisting of 76.9 mass % of SUPER NANOX manufactured by Lion Corporation and 23.1 mass % of polyoxyethylene monolaurate (Emanon 1112 (registered trademark) manufactured by Kao Corporation; the water content of the liquid detergent after preparation was 28 mass % and pH 7.4) or 70 g of powder detergent (Cucute (registered trademark) soaking powder (trade name) manufactured by Kao Corporation, pH 10.5), and a water-soluble film sample piece cut to 39 mm x 32 mm was sealed so that it was in complete contact with the detergent, and the bottle was then capped with a plastic lid. Next, each glass bottle containing the detergent and the water-soluble film sample was stored under an environment of 40°C and 80% RH for 14 days, after which the detergent-contacted water-soluble film sample was removed from the glass bottle and the detergent was wiped off. These detergent-contacted water-soluble film sample pieces were each sandwiched between two rectangular plastic mounts with 34 mm x 23 mm windows, respectively, so that the windows were blocked, and then fixed to a hanging jig. Then, a 1 L beaker containing 800 mL of distilled water was placed in a water bath maintained at 20°C and stirred with a stirrer (stirring bar length: approximately 5 cm, rotation speed: 400 rpm). The detergent-contacted water-soluble film sample piece fixed to the plastic mount attached to the hanging jig was immersed in water in the water bath, and the time point at which any one part of the detergent-contacted water-soluble film sample piece broke was measured as the dispersion time after detergent contact treatment (dispersion time of the detergent-contacted film). After checking the dispersion time, the plastic mount was struck up and down to knock the detergent-contacted water-soluble film sample off the plastic mount, so that the detergent-contacted water-soluble film sample floated in water. The time when the detergent-contacted water-soluble film sample was completely dissolved and no residue could be visually detected was measured as the complete dissolution time after detergent contact treatment (the time when the detergent-contacted water-soluble film was completely dissolved). Note that this "dissolution" also includes the case where insoluble fine particles with a diameter of 1 mm or less were dispersed at the time when the detergent-contacted water-soluble film sample was no longer visible.The moisture content of the liquid detergent was measured using a Karl Fischer method moisture meter AQV-2200s (trade name, manufactured by Hiranuma Sangyo Co., Ltd.), and the pH of the liquid detergent and powder detergent was measured in accordance with JIS K 3362 8.3 using a pH meter LAQUAact D-74 (trade name, manufactured by Horiba, Ltd.) after measuring 0.5 g of the detergent and dissolving it in 50 ml of pure water to prepare an aqueous solution, adjusting the temperature of the resulting aqueous solution to 25°C.

[0050]

[0051] As is clear from Tables 1 to 4, capsules made of water-soluble films No. 1 to No. 14 within the scope of the present invention are superior to capsules made of water-soluble films No. 16 using unmodified PVA resin. ＊ Compared with capsules using the water-soluble film No. 1, the complete dissolution time after 14 days of contact with liquid detergent was 246 seconds or less, and the difference between the initial complete dissolution time and the complete dissolution time after 14 days of contact was 182 seconds or less. Furthermore, the complete dissolution time after 14 days of contact with powder detergent was 78 seconds or less, and the difference between the initial complete dissolution time and the complete dissolution time after 14 days of contact was 35 seconds or less. Thus, the water-soluble films No. 1 to No. 14 have good solubility.

[0052] (Method of forming capsules) Two sheets of the formed water-soluble film with a thickness of 75 μm were used to form a packaging capsule. The first sheet of water-soluble film was stretched without any wrinkles or sagging, and a cavity (opening area 2000 mm ) was formed. ２ The water-soluble film was placed on a mold having a box-shaped cavity (a 15 mm deep cavity with rounded corners) so that the casting surface (the surface that comes into contact with the metal roll during film formation) faced the inner wall of the cavity. The water-soluble film was heated at about 90°C for 5 seconds, and conformed to the cavity by vacuum forming to form a water-soluble film for the bottom having a recess. The recess was then filled with about 22 mL of the previously prepared liquid detergent B. Next, a second piece of water-soluble film was used as the water-soluble film for the top. Water was applied to the air side (the surface that comes into direct contact with air during film formation) of the water-soluble film using a water-moistened lab towel (trade name, manufactured by Unichemy Co., Ltd.) to an amount of 44 to 54 g / m. ２The water-coated surface of the top-water-soluble film and the peripheral surface (air-facing side) of the bottom-water-soluble film, which had been set in the cavity and filled with liquid detergent B, were then pressed together using a 1.5 kg metal roll, and the resulting mixture was held for approximately 1 minute and 30 seconds. The vacuum was then stopped, and the capsule was removed from the cavity to produce the spindle-shaped liquid detergent capsule shown in Figure 1(a). Liquid detergent B consisted of 18.6% by mass of SUPER NANOX manufactured by Lion Corporation, 75.4% by mass of polyoxyethylene monolaurate (Emanon 1112 (registered trademark) manufactured by Kao Corporation), and 6.0% by mass of glycerin manufactured by Sakamoto Pharmaceutical Industry Co., Ltd. The moisture content of the prepared liquid detergent was 8.9% by mass and pH 7.7.

[0053] (Method for measuring capsule height) After removing the liquid detergent packaging capsule from the cavity, it was left to stand at room temperature for about 7 minutes. At this time, the initial height (h1) of the spindle-shaped liquid detergent-enclosed capsule shown in Figure 1(a) was measured using a height gauge (Mitutoyo Corporation: Absolute digital height gage). This liquid detergent packaging capsule was further stored in an environment of 23°C and 50% RH for 7 days. At this time, the height (h2) after storage of the liquid detergent packaging capsule shown in Figure 1(b) was measured using a height gauge (Mitutoyo Corporation: Absolute digital height gage). The initial height (h1), post-storage height (h2), difference between the post-storage height (h2) and the initial height (h1), and residual rate (h2 / h1 x 100) of the liquid detergent packaging capsule are shown in Table 5.

[0054]

[0055] As is clear from Table 4, the capsules made of water-soluble films No. 1 to No. 14, which are within the scope of the present invention, have a height residual rate higher than that of No. 15, which has a maleic acid-modified monomer unit content outside the range of the present invention. ＊ The capsules were higher and more taut than those made with the water-soluble film.

[0056] The water-soluble film for packaging medicines according to the present invention can be suitably used as a packaging bag for detergents (liquid and powder), agricultural chemicals, and the like.

[0057] h1: initial capsule height, h2: capsule height after storage

Claims

1. A water-soluble film for pharmaceutical packaging comprising a water-soluble resin in which a plasticizer (B) is blended with a polyvinyl alcohol resin (A), wherein the polyvinyl alcohol resin (A) has a degree of saponification of 85 to 96 mol%, a 4% aqueous solution viscosity of 6 to 50 mPa·s, and contains 0.2 to 1.6 mol% of maleic acid-modified monomer units, and the blending amount of the plasticizer (B) is 5 to 50 parts by mass per 100 parts by mass of the polyvinyl alcohol resin (A), and the moisture content of the film is 4.0 to 10.0% by mass.

2. The water-soluble film for packaging medicines according to claim 1, characterized in that the polyvinyl alcohol resin (A) is a maleic acid-modified polyvinyl alcohol resin.

3. A water-soluble film for packaging pharmaceuticals as described in claim 1, characterized in that the amount of maleic acid-modified monomer units contained in the polyvinyl alcohol resin (A) is 0.2 mol % or more and less than 1.0 mol %.

4. The water-soluble film for packaging medicines according to claim 1, characterized in that the plasticizer (B) is glycerin (B-1) or glycerin (B-1) and diglycerin (B-2).

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